Liquid fuel injector



Nov.u2`7, 1934. F. RITZ LIQUID FUEL INJECTQR Filed July 2'7',- 19.51

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0 a w (in 4 l/ NOV. 27, 1934. F, RITZ 1,982,023

` LIQUID FUEL INJEGTOR l Filed July 27, 1931 :s sheets-sheets Patented Nov. 27, 1934 UNITED STATES PATENT OFFICE This invention relates to liquid fuel injectors for internal combustion engines and has particular reference to a combined pump and nozzle for injecting liquid fuel into the combustion chambers of a Diesel engine or the like.

The principal object of the present invention is to provide an injector of the type described embodying features directed to more satisfactory and flexible operation of the injector, to provide means for limiting the stroke of the needle; to provide improved means for securing the fuel conduits to the injector; to provide novel means for varying the start and close of the injection; to provide means for preventing gas from passing from the combustion chamber into the injector, to interfere with the operation thereof; improved means for cooling the nozzle tip.

Other objects and attendant advantages will become apparent from the following description, the claims, and the accompanying drawings, in which- Figure 1 is a longitudinal section through one embodiment of my invention showing the injector positioned in the walls of an engine cylinder; 25 Fig. 2 is a top view of Figure 1;

Fig. 3 is a. section on the line 3-3 of Fig. 1 showing the fuel regulating ring;

Fig. 4 is a section on the line 4-4 of Fig. 1 showing the pipe connecting collar;

Fig. 5 is a section on the line 5 5 of Fig. l showing the fuel circulating grooves;

Fig. 6 is an enlarged section of the lower end of the embodiment shown in Fig. 1;

Fig. 'I is a section through the lower end of a 35 modled form wherein the nozzle tip is removable from the lower end of the injector;

Fig. 8 is a longitudinal section through one unit consisting of the casing, the pump handle, the nozzle tip, and the feed regulating ring;

Fig. 9 is a side view of the needle stopping mechanism;

Fig. 10 is a longitudinal section through the Fig. 11 is a side view of the needle and plunger -5 assembly; y

Fig. 12 is a view of the cylinder walls showing the pipe connecting collar in position to receive the parts shown in Figs. 8 to 11, inclusive, in assembling the device;

0 Fig. 13 is a diagrammatic view of a suitable type cf fuel supply system;

Fig. 14 is a longitudinal section through a second embodiment of my invention;

Fig. 15 is a section on the line 15-15 of Fig. 14

. i-.showing the rocker arm and rocker arm flanges;

Fig. 16 is a section on the line 16--16 of Fig. 14 f showing the pipe connecting collar;

Fig. 17 is a section on the line 17-17 of Fig. 14;

Fig. 18 is a perspective view of the lower end of the pump plunger; and

Fig. 19 is a development of the grooved surface of Fig. 18 showing, in dotted lines, the position of the fuel supply openings in the pump cylinder.

Referring first to Fig. 13, the invention provides a fuel supply system for internal combustion engines of the Diesel type having one or more injectors designated generally by the numeral 21. arranged to be actuated by means of rocker arms for the injection of liquid fuel into the cylinders of the engine. The injector units are so designed that the fuel injected into the combustion chamber comprises only a portion of the total fuel supplied to the injector, the remainder thereof being circulated about the nozzle tip for the purpose of keeping the temperature of the tip sufficiently low as to substantially prevent the .decomposition of the fuel and the clogging of the orifices. The means external from the injector for supplying the liquid fuel consists of three manifold tubes designated generally by the numerals 22, 23 and 80 24, the manifold 22 being connected to the outlet side of the injector by means of a pipe 25, the manifold 23 to the inlet side ofthe injector by a pipe 26 and the manifold 24 to the drain side of the injector by a pipe 27. Liquid fuel is `pumped through the manifold pipe 23 from a fuel container 28 by means of a low pressure pump 29, an oil filter 31 being interposed in the line 23 to filter the fuel before it enters the manifold. The fuel passes from the manifold 23, through the pipe 26 90 into each of the injectors 21. After passing through the injector, as will presently be described, the fuel emerges through the pipe 25 and passes into the manifold pipe 22, through which it is returned to the fuel container 28. A plurality of cooling. fins 32 may be positioned upon the pipe 22 for the purpose of cooling the fuel before -its return to'the fuel container 28. Obviously,

other means may be employed for cooling the fuel, The manifold 24 is likewise connected to 100 the. fuel container 28 and serves to conduct fuel which leaks by the plunger of the injector, as will presently be described, back into the container 28.

Referring now more particularly to Figs. 1 to 6, 105 inclusive, one embodiment of the invention consists of a casing 33 having a variable internal diameter arranged to receive the various parts presently to be described. The lower end of the Casing 33 is arranged to be received in the /cylv110 2 inde-r walls 34 oi an internal combustion engine between the cooling chambers and 36 thereof and to have its lower end 37 face the combustion chamber. The casing 32 may be tapered, as

`shown at 38, if desired, to provide a seat against ber 39 and projects out throughthe opening 41 closing the same, the nozzle tip being provided with annular-shoulders 43 and 44. The shoulder 43 bears against the end of the casing 33 and is held firmly there against through contact of the shoulder 44, of the lower end 45 of a pump cylinder designated generally by 46 and presently to be more fully described. The tubular wall 47 of the nozzle tip extends upward within the pump cylinder 46 a short distance providing a cylindrical chamber 48 arranged to receive the lower end of a needle designated generally by 49 and a check valvehaving a sleeve 51 slidably receivable within close limits in the chamber 48. A coiled spring 52 acts between the end of the nozzle tip 42 and the sleeve 51 to urge the sleeve upward against a shoulder 53 on the needle, thereby normally closing the chamber 48 against movement of gas or liquid upward through this chamber. The lower end of the nozzle vtip 42 is provided with a passage 54 normallyarranged to be closed by the conical point 55 of the needle 49, a plurality of orillces 56 serving to permit the exit of uidfrom the chamber 48 through the passageway 54 into the combustion chamber of the engine when the needle 49 is unseated.

y The pump cylinder 46 is positioned within the casing 33 and closely fits the inner wall thereof to substantially prevent the passage oiliquid along the interface. The cylinder is held within the casing by means of a nut 57 which has threaded engagement with the casing and bears downward against the upper end ofthe cylinder forcing the lower end 45 thereof against the shoulder 44 4of the and 63 extend from the nozzle tip. Slots 64 in the upper end of the nut serve to receive a Spanner wrench for the purpose of tightening the nut. A gasket 58 is positioned at the junction of the nut 57, the cylinder 46 and the casing 33 to further prevent the iiuid from passing out from between `the cylinder and the casing. The nut 57 is tightened upon the gasket 58 to compress it and-form a liquid tight. junction. Opposite sides of the cylinder 46 are provided withA longitudinal slots 59 and 61 which extend from the lower end thereof to a point near but spaced from the upper end and fuel supply openings 62 slots 59 and 61 to the interior oi the cylinder as best shown in Fig. 5. The slots 59 and 61 serve to conduct fuel into and out 'of the chamber 39 and to permit the passage of fuel into the pump cylinder 46 from which it is suppliedto the combustion chamber as will presently be more fully explained.

A pump plunger numeral 65 consists of a tubular member positioned in the pump cylinder 46 and arranged to be reciprocated therein. The plunger should be received in the cylinder within very close limits so that when pressure is applied to the fuel by downward movement of the plunger a minimum amount of the liquid will pass along the walls of the cylinder. The lower end of the plunger wall is provided with a metering head 66 presently to be more fully described, arranged to cooperate with the openings 62 and 63 to regulate the amount of fuel designated generally by the Y which will be injected into the combustion chamber upon reciprocation of the plunger 65. The upper end of the plunger is provided with a feed regulating projection 67, projecting laterally from the plunger and a threaded portion 68 arranged to be received in the threaded end 69 of a spring cage 71. Theupper end of the spring cage is provided with a threaded portion 72 arranged -to `receive a threaded spring retaining end 73. 'I'he end 73 is provided with an axial opening 74 for a purpose which will presently become apparent and with a ball race arranged to receive ball vbearings 75, which racilitate rotation ofthe spring cage and associated parts. The lower end of the spring cage 7l isprovided with a plurality of openings 76 to permit the escape of uid which may have gained access to the interior of the cage. A cylindrical cap 77 having an open lower end and a closed upper end provided with an axial opening 78 is positioned over the upper lend of the cage 7l, the side walls of the cap 77 illling the space between the cage 71 and the casing 33, the arrangement being such as to permit longitudinal reciprocation of the cage 7l and the cap 77 within the casing.

. The needle 49 is positioned axially withinthe plunger 65 and is provided with the conical point 55, the shoulder 53, a shoulder 79 and an upper end 81 of such length as to projectinto the spring cage 71. A spring retainer having a cylindrical portion.82 and a flange portion 83 is positioned over the vend .8l of the needleA within the spring cage 71, the flange 83 being arranged to receive one end of a compression spring 84 within the cage 7l. 'I'he upper end of the ,spring 84 is adapted to bear against the spring retaining end 73, the arrangement being such that when the pressure of the spring 84 against the ange 33 and consequently against the needle 49 is increased.'

Obviously the spring cage may be eliminated if desired, by extending the plunger upward within the spring or by other suitable means whereby the spring is placed outside of the member receiving the rocker arm. lf desired, the needle 49 may be formed of two portions as shown in Fig. l, the lower portion 85 having the tapered end 55 and the shoulders 53 and 79 and being cut as shown at 86 to provide a point contact with the upper portion 87 thereof. This eliminates the tendency to bend under excessive pressure, a tendency common in long needles. By providing the needle in two or more parts this tendency is eliminated.

In order to limit the longitudinal movement oi the needle I have provided a collar 88 threaded to the upper end of the casing 33 and secured against movement by a nut 89, the collar having an arm 91 projecting over the end of the casing and provided with a rod 92 extending through the axial openings 74 and 78 into the cage 7l to a point spaced from the spring retainer 82. The roei. 92 has threaded engagement with the arm 9i 2nd is provided with a nut 93 to permit ofvarixtior of the longitudinal position of the rod 92 and allow adjustment of the needle stroke. It will be seen, that when the needle 49 is raised, it will come into contact with the lower end of the rod 92 which will thus limit the further movement of the needle. This stop prevents the needle from being excessively raised upon each injection of fuel and thereby eliminates the pounding or noisy operation of the valve caused by such excessive movement. Other functions of the stop will be hereinafter fset forth.

The amount of fuel injected into the combus tion chamber is varied through rotation of the pump plunger as will presently more fully appear. This rotation is brought about by contact of the feed regulating projection 67 with a feed regulating ring designated generally by the numeral 94. This consists of a cylindrical ring arranged to bear at its lower edge against a face 95 on the inner side of the casing 33 and at its upper edge against a snap ring 96 positioned in a groove 97 on the inner side of the casing 33. Openings 98 are provided to permit the snapping out of the ring 96 and thereby the assembly and removal f the feed regulating ring 94. The feed regulating ring is provided with a slot 99 arranged to receive the projection 67 for longitudinal movement and to permit rotation of the plunger 65 through rotation of the feed regulating ring. This rotation is brought about through movement of a feed regulating arm 101 passing through an opening 102 in the casing 33 and having threaded engagement with the feed regulating collar as shown at 103.

Fuel enters the injector through a pipe 26 and is conducted through the casing 33 to the longitudinal groove 61 by means of a channel 104 and leaves the injector through a pipe 25, passing from the groove 59 to the pipe 25 through a channel 105 'as best shown in Fig. 4. The fuel leaking from the grooves 59 and 61 and passing upward between the casing and the pump cylinder 46, between the pump cylinder and the plunger 65, and between the plunger and the needle 49 fiows into a passageway 106 and is conducted Out of the injector through a pipe 27. In order to do away with the difficulty attending the removal of the pipes 25, 26, and 27 from the injector, when the injector is vremoved from the engine, I have provided novel means for connecting these pipes to the injector. This consists of a pipe connecting collar 107 positioned around the casing 33 at a point adjacent to the engine, or, if desired, the collar may be secured directly to the cylinder head with a piece of heat insulating material between. The collar is provided with a series of openings to receive the pipes 25, 26, and 27, the openings being so positioned as to register with the channels 104 and 105 and 106 when the collar is properly positioned upon the casing. The collar is slit as shown at 108 and opposed flanges 109 and 111 are positioned on the ends of the collar, the flanges being connected at their outer ends as shown at 112. The flange 109 is provided with an opening 113 to receive a threaded bolt 114 arranged to engage a threaded opening 115 on the flange 111. A nut 116 is arranged to be turned to screw the bolt 114 into the flange 111 and draw the two ends of the collar together, thus tightening the collar about the casing 33, so that leakage from the junction between the channels 104, 105, and 106, and the openings in the collar is substantially prevented. The tubes 25, 26, and 27 are flxedly and permanently secured in the openings of the collar.

It will be seen that when the slot 114 is loosened the collar will be loosened on the casing and the injector may be withdrawn from the engine and from the collar without. in any way, disturbing the position of the pipes or the collar, as shown in Fig. 12. 1f desired, channels corresponding to the pipes 25, 2G, and 27, may be located in the cylinder wall of the engine and arranged to coincide withithe channels 104, 105 and 106, at points below the level of the cylinder walls to completely eliminate the collar 107. This, however, has the disadvantage that the fuel is heated by the hot cylinder walls before it enters the injector.

Referring now more particularly to Figs. 18 and 19, I have provided novel means for measuring the fuel to be injected and for determining the time at which the injection will start and the time at which the injection closes. Th'zs consists of a metering head having a slot of novel shape characteristics on the surface of the plunger 65, the circumference being slotted to provide two upstanding blocks designated generally by the numerals 117 and 118 of identical shape. In the slot projection shown in Fig. 19, each of the blocks is provided with a circumferential edge 119, a longitudinal edge 121, a second circumferential edge 122 corresponding with the lower end of the plunger, a lower sloping edge 123, an upper sloping edge 124 and a second longitudinal edge 125. These edges are arranged to cooperate directly with the fuel sup-J plyl openings 62 and 63 to measure the fuel being injected into the combustion chamber. Itl will be seen that with the openings 62 and 63 and the plunger 65 in the relative position shown in Fig. 19, downwardmovement of the plunger will result in no pumping action. However, rotation of the plunger will cause the sloping edge 123 to pass over the openings 62 and 63 as the plunger moves downward so that the blocks 117 and 118 will close the openings 62 and 63 until the edge 124 begins to pass over the openings 62 and 63. Thus during the period when the blocks ,cover the openings the fuel will be entrapped beneath the plunger and will be forced into the combustion.

chamber until the edge 124 uncovers the openings and releases the pressure. As the plunger 65 is turned further toward the right, the sloping edge 123 will cause the injection to start at an earlier point in the downward movement of the plunger, thereby causing an earlier injection of fuel into the combustion chambers as the amount of fuel being injected increases. The

sloping edge 124 causes the plunger to move further downward in its stroke before the pressure on the fuel beneath the plunger is released, thereby increasing the amount of the fuel being injected. The head may be made with only a\ single upstanding block, if desired, two being herein employed to equalze the pressure around the plunger. It will also be observed that it is probably desirable to employ the lower sloping edge 123 only on engines wherein the load varies directly with the speed as in propeller engines and the like.

Referring again more particularly to Figure 1, during the normal operationvof an'engine provided with my injector, the cap 77 and the cage 71 are reciprocated longitudinally by means of a rocker arm havng contact with the upper end of the cap. Upon downward movement of the fices 56 into the combustion chamber of the en- Fuel is circulated through the injector by gine. way of the pipe 26, the channel 104, the groove 61, the chamber 39, the groove 59, the channel 105 and the pipe 25. The amount of fuel thus circulated is considerably greater than the amount being injected by the plunger 65, this excess serving to mainta'n the nozzle tip 42 at a lower temperature than would otherwise be the case. By maintaining the nozzle tip at a relatively low temperature, decomposition of the fuel in the chamber 48 and in the orifices 56 is substantially prevented. Fuel is supplied to the injection chamber beneath the plunger through openings 62 and 63, the pressure of the fuel being rapidly released, thereby causing the needle to seat suddenly under the increased pressure of the spring 84. However, should the needle fail to properly seat so as to completely prevent gases from the combustion chamber from passing through the orifices 56 back into the pump cylinder 46, the check valve 51 will prevent the gas from proceeding beyond the shoulder 53. This prevents the gases from proceeding backward into the fuel supply system to a point where they will not be expelled upon the next operation of the plunger. In other words, the check valve 51 prevents the fuel supply system from becoming air bound. Another advantage of my improved construction lies in the fact that means are provided for preventing excessive movement of the needle 49. It will be seen that should the orifices 56 become partly stopped with carbon or the like, the rate of flow through the orifices will be decreased whereupon the pressure on the fuel as the plunger moves downward will be abnormally increased. This will tend to cause excessive upward movement of the needle so that when the pressure on the fuel is released at the end of the plunger stroke, the needle will have reached a point conl siderably higher than normally desirable and will be brought to the closed position with considerable force. This tends to produce noisy operation. For this reason, the rod 92 is provided to prevent this excessive movement. The effect of this stop is also to prevent the high pressure on the fuel from being relieved by such excessive movement, since if this pressure is not relieved a greater amount of fuel will be injected through the orifices in unit time, thus at least partially compensating for the decreased size of the orifices.

A further advantage of this construction lies in lthe fact that the feed regulating projection 67 is formed directly on the plunger 65 so that the plunger must always be positioned in the injector in identically the same position with respect to the fuel supply openings 62 and 63. Because of this it is unnecessary to adjust the position of the plunger each time the plunger is removed from the injector. In other words, whenever the injector is assembled the relationship between the fuel supply openings 62 and 63,'the blocks 117 and 118, and the feed regulating ring 94 will be identically the same so that at a predetermined setting of the ring 94 the same amount of fuel will always be injected into the combustion chamber.

Another advantage of this construction lies in its ease of assembly and disassembly. 'Ihis is shown in Figs. 8 to 12, inclusive. Thus in assembling the injector the part shown in Fig. 1-1 is slipped into the part shown in Fig.. 8, the cap shown in Fig. 10 is passed over the part shown in Fig 11, with the ball bearings in place, the part shown in Fig. 9 is then screwed onto the top of the casing, and the injector is inserted through the pipe connecting collar and into the cylinder wall shown in Fig. 12.

A further advantage of this embodiment of my invention. lies in the fact that the fuel regulating ring 94 is positioned on the inside of the casing 33 and held therein by means of the spring ring 96. This arrangement results in substantial advantages in that the present fuel regulating sysinvolved since, in many instance, only very tem may be employed for rotating the plunger 65. While other means may be employed, I have found this to be of particular advantage in the increased accuracy of thefeed control. When gears or the like are employed, there is always a certain amount of play in the mechanism which reduces the accuracy of the injection. -In this construction the projection 67 fits very closely in the ring 94 and substantially eliminates this objection. Furthermore, this construction is relatively cheap to manufacture and singularly free fromv operating difllculties.

The injector will be seen to occupy but a small amount of space on the cylinder head. This is a matter of importance in engines of the type small space is available for the nozzle.

Particular attention is also directed to the manner in which the fuel supply pipes are connected to the injector. By the means employed the injector may be quickly and conveniently removed and replaced without, in any way, bending or distorting the pipes, thereby substantially eliminating the danger of leaks and breakage.

Referring now to Figure 7, I have shown a modifled form of injector wherein the nozzle tip may be removed directly from the lower end of the injector. In this case the casing 33 is provided with a cylindrical chamber 127 surrounding the pump cylinder 46, the lower end of the pump cylinder having bearing in the lower threaded end 128 of the casing 33. A flange 129 is positioned at the lower extremity of the pump cylinder and bears against the end of the threaded portion 128. The nozzle tip 42 is held against the flange 129 and within the pump cylinder by means of a threaded end 131 screwed onto the threaded portion 128 of the casing. A packing 132 is positioned between the end 131 and the casing 33 to prevent the loss of fuel between 'these members. The fuel, which is under low pressure, passes between the chamber 127 andv the chamber 39 through channels 133 for the purpose of circulating oil through the chamber 39 to cool the nozzle tip. 'I'his construction offers the advantage that the nozzle tip 42 may be removed from the injector without removing the pump cylinder 46 or the remainder of the mechanism.

Referring to Figs. 14 to 17, inclusive, I have shown, another embodiment of my wherein the casing consists of an upper portion 134 and a lower portion 135 arranged to be received within the former, a shoulder 136 being adapted to be held against the lower end of the portion 134 by means of a nut 137 having a flange 138 arranged to hold the shoulder in place. In this instance the casing is provided with a top 139 having a rod 141 axially positioned therein by means of a threaded portion 142 and a nut 143 to permit longitudinal adjustment of the position of the rod 141. A spring cage 144 is provided with a top 145 against which a spring 146 is adapted to bear, and is provided with an axial opening 147 through which the rod passes. The cage is provided with oppositely extending arms 148 and 149 arranged to project through slots 151 and 152 in the casing portion 134. A bifurcated rocker arm 153 is arranged to have the ends 154 and 155 thereof press upon the arms 148 and 149 to reciprocate the same longitudinally of the injector.

In this embodiment a shoulder 156 is'fOrmed on the plunger arranged to provide a bali race for the ball bearings 157. The feed regulating projection 67 is formed on the shoulder 156. A

invention a ball retainer'8` having a curved top is positioned over the balls 157 and is adapted to cooperate with the shoulder 156 to maintain the mechanism in suitable alignment. 'I'he lower end 159 of the spring cage 144 is provided with a central opening to receive the plunger and with a curved face to bear against the curved upper side of thel ball retainer 158. l A pair of nuts 161 and 162 are threaded on the upper end of the plunger and serve to secure the lower end 159 of the spring retainer, the ball retainer 158, the balls 157 and the shoulder 156 together. The curved surface on the ball retainer serves to permit of easy alignment between the spring retainer and the plunger, permitting a certain amount of angular movement between these parts.

The needle 49 .is provided with a recess 163 at a point above the highest possible position of the measuring end of the plunger 65 and a circumferential slot 164 is formed on the outer side of the plunger 65 as shown in Fig. 14. A channel 165 passes through the plunger at the lower edge of the slot 164 whereby to connect the slot and the recessed portion 163 when the plunger moves toward the lowermost point of its stroke and the needle moves upward under the influence of the pressure thus created on the fuel. An opening 166 .connects the slot 164 with the longitudinal slot 59 so that when the plunger moves toward the lowermost point of its stroke the depression 163 will be connected to the longitudinal slot 59 permitting fuel which may have passed along the interface between the needle and the plunger and between the plunger and the cylinder to pass outward into the longitudinal slot 59. This will relieve the pressure on the fuel along the interface between these parts, which pressure will be relatively high because of the high pressure on the fuel within the pump cylinder. On the other hand, the fuel is circulated through` the longitudinal slots 59 and 61 at relatively low pressures so that there will be a substantial pressure differential between these two points.

The feed regulating ring 94 is held into the casing in the latter embodiment in a slightly different manner than shown in Fig. 1. In the embodiment shown in Fig. 14 the ring is inserted from the lower end of the portion 134 and bears at its upper edge against a circumferential shoulder 167. The upper edge 168 of the casing portion 135 bears against the lower edge of the feed regulating ring 94 to maintain it in position.

In the second modification it will be seen that the plunger is actuated from a point intermediate the ends of the injector. For this reason this embodiment 4is best adapted for use where the amount of space is limited since the injector may be made of a substantially lesser length and since the necessity for space at the end of the injector for operation of the rocker arm is unnecessary.

Another advantage of the second modification lies in the fact that the plunger is actuated from opposite sides of the injector whereby there is no side thrust on the plunger such as is caused by an actuation. not directly in line with the movement of the plunger.

It will also be observed that in this instance the casing is formed of two parts connected at the center whereby the manufacturing costs of the casing and the assembling thereof is substantially reduced.

Another feature of this embodiment is the fact that the drain fuel is conducted back into the fuel return line so that no special fuel line need be provided for returning the drain' fuel to the fuel container. Furthermore, novel means are provided for relieving the pressure on the fuel at the interface between the moving parts so that this fuel is not forced up into the remainder of the injector.

It will further be observed that this embodi ment possesses substantially all of the major advantages of the embodiment shown in Fig. 1, the arrangement of the parts being slightly different so as to accomplish a reduction in the overall length of the injector and rocker arm, to permit its use in smaller space.

While I have thus described and illustrated a specific embodiment of my invention, I am aware that numerous alterations and ,changes maybe made therein without materially departing from the spirit of the invention and the scope of the appended claims; in which- I claim:

1. In an injector of the solid injection type, a casing having a fuel supply chamber and an orifice at the lower end thereof, a differential needle within said chamber arranged to close said orifice, and means for trapping gas entering said chamber through said orifice.

2. In an injector of the solid injection type, a casinghaving a fuel supply chamber and an injection orifice, a needle within said chamber ari ranged to close said orifice, means for compressing the fuel in said chamberto lift said needle and force a predetermined amount of fuel through said orifice, and a check valve acting between said casing and said needle for trapping gas entering said chamber through said orifice.

3. In an injector of the solid injection type, a casing having a fuel supply chamber and an injection orifice at the lower end thereof, a differential needle within said chamber arranged to close said orifice, a shoulder on said needle facing said orifice, a sleeve slidable'in said chamber concentric with said needle between said shoulder and said orifice and movable between a closed position against said shoulder and an open position, and means for normally holding said sleeve in the closed position to prevent the passage of gas along said needle.

4. In a device of the character described, a casing having an orifice, a plunger within said casing arranged through longitudinal reciprocation to force fuel through said orifice in amounts dependent upon the axial position thereof, and means for regulating the angular position thereof comprising a collar on the inside of said casing, a peripheral shoulder on the inside of the casing providing a seat for the collar, a snap ring arranged to seat in the casing above the collar to maintain the collar against its seat, means for rotating said collar within said casing, a slot in said collar, and a lateral projection on said plunger longitudinally movable in said slot arranged to be moved axially with said collar to bring about rotation of said plunger.

5. In an injector of the solid injection type, a casing provided with an orifice, a hydraulically opened differential needle within the casing arranged to normally close the orifice, and means for forcing a measured quantity of fuel through said orifice comprising a pump cylinder connecting with said orifice having at least one fuel supply opening, and a plunger surrounding said needle reciprocable thereon in said cylinder havylili ing a metering head provided with means for advancing the time of injection as the amount of fuel injected increases.

8. In an injector of the solid injection type, a easing provided with an orifice, a hydraulically opened differential needle within the casing arranged to normally close the orifice, and means for forcing a measured quantity of fuel through said orifice comprising a pump cylinder connected with said orifice having at least one fuel supply opening, a plunger surrounding said'needle reciprocable thereon in said cylinder, means for rotating said plunger. and a'metering head on said plunger comprising acircumferential slot therein, at least one longitudinal slot, said circumferential slot having a lower edge provided with a diagonal portion joiningsaid longitudinal slot, and a diagonal slot joining said longitudinal slot below and opposed'to said diagonal edge, said slots and said fuel supply opening serving to regulate the amount of fuel injected and the time of the start and close of the iniection through rotation of said plunger.

7. In a device of the character described the combination of a casing provided with a fuel supply chamber and an orifice for supplying liquid fuel to an engine cylinder, a plunger in said chamber arranged to be reciprocated to force fuel through the orifice, a needle passing through said plunger arranged to be held in a closed position to close said orifice and be opened through 'pressure on the fuel in said chamber, spring means acting between the needle and the plunger for normally holding said needle in the closed position and stationary means for limiting the movement of said needle.

8. In a device of the character described having a casing provided with a fuel supply chamber and an orifice for supplying liquid fuel to an engine cylinder, a plunger arranged to periodically place pressure on said fuel, a needle arranged to occupy a closed position closing said oriilce and be opened through pressure on said fuel, spring means acting between said needle and said plunger for normally holding said needle in the closed position, and means acting between said casing and said needle for limiting the movement of said needle to determine the open position.

9. In a device of the character described com- Dri-*11D8 a casing unit provided with a fuel supply chamber, on orifice for supplying liquid fuel to an engine cylinder, and a needle stop member and a plunger and needle unit slidable from the casing upon removal of said needle stop member comprising a needle arranged to close said oriilce. a plunger in said chamber and around the needle for placing a pressure on' said fuel, spring means for normally maintaining said needle in the closed position, said stop'member limiting the open position thereof, and a pair of arms connected to said plunges intermediate the ends of said unit extending through said casing and kadapted to receivea rocker arm to reciprocate said plunger.

10. Ina device of the character described, a casinghavinga fuel supply chamber and an orice facing the combustion chamber of an engine, pump means in the casing for forcing fuel in vsaid supply chamber through said orifice, means for circulating fuel near said orifice to cool said casing adjacent said orifice, and means for conducting a portion of said circulating fuel into said fuel supply chamber.

11. In a device of the character described, a casing, a nozzle tip at the inner end of said casing having an orifice connecting with the combustion 1,osa,oas

chamber of an engine, a fuell supply chamber in said casing communicating with said orii'ice, means for forcing fuel from said fuel supply chamber through said orifice, a cooling chamber surrounding said noule tip, means for circulating fuel through said cooling chamber, and a com'-v municating opening for conducting a. part of said circulating fuel into said fuel supply chamber.

12. In a device -of the character described, a casing having a fuel supply chamber and an oriilce, a plunger in said chamber arranged to be reciprocated to periodically force a measured quantity of fuel from said chamber through said orifice, a needle axially positioned in said plunger arranged to normally close said orifice and be lifted by the pressure of said fuel. said needle being provided with a circumferential slot to collect the fuel passing along the interface between said needle andsaid plunger, and said plunger being provided with a circumferential slot and an opening at the lower edge thereof positioned to communicate with the slot in said needle and receive the fuel therein when said needle is lifted. and means for conducting the fuel from the slot in said plunger. 1

13. An injector for internal combustion engines comprising in combination, a casing adapted to be positioned in the cylinder walls of an engine, a nozzle tip positioned in and bearing against the inner end of said casing, having an orifice connecting with the combustion chamber of said engine, s.` pump cylinder in said casing, an externally threaded nut in said casing for holding said pump cylinder therein and against said nozzle tip, a plunger in said pump cylinder arranged to no be reciprocated to pump fuel through said orince, and a needle in said plunger normally closing said oriilce and opened by the pressure of said fuel.

14. 'Ihe combination claimed in claim 13 in which combined means are provided for circulating fuel around said nozzle tip to cool the same and for supplying fuel to said pump cylinder.v

15. The combination'claimed in claim 13 in which said casing is provided with al cooling m chamber around said nozzle tip, means for conducting fuel to and away from said chamber, and means are provided for cooling said fuel for recirculation through said injector.

16. In an injector of the solid injection type, m

a casing having an orifice, a plunger within said casing arranged through longitudinal reciproca- 'tiontoforcefuelthroughsaidorinceinamoimts dependent upon tbe axial position thereof, means for reciprocating the plunger. means for regulating the angular position thereof, and an antifriction thrust bearing between the plungerl and said first mentioned means to facilitate rotation of the plunger.

17. In an injector or the sona injection type. m

a casing having a fuel supply chamber andan injection orifice facing the combustion chamber of an engine, pump means in the casing for forcing fuel from said supply chamber through said orifice, a cooling chamber in said casing I surrounding said orifice, means for circulating fuel under low pressure through said last mentioned chamber to cool said casing adjacent the orifice, and means for conducting a portion of said circulating fuel into said fuel supply chamber l for injection into the-engine.

18. In a injector of the solidinjection type, a casing provided with .a fuel supply chamber and an orifice for supplying liquid fuel to an engine cylinder, a valve closing said oriilce, a reciprow cable plunger in said chamber for injecting fuel through said orifice, and combined means for circulating fuel in said casing around said orifice to cool the same and for supplying fuel to said su'pply chamber.

19. In an injector of the solid injection type, a casing provided with a fuel supply chamber and an orifice for supplying liquid fuel to the engine cylinder, a valve closing said orii'ice, a reciprocable plunger in said chamber for injecting fuel 

